1. Technical Field
The invention relates to a piston ring, in particular a compression piston ring.
2. Related Art
The running surfaces of piston rings, in particular compression piston rings in internal combustion engines, experience a particular stress on the ring joint ends due to thermal and mechanical impingement. This typically results in excessive wear at this location and possibly thermal overload and subsequent corrosion. The joint area is therefore one of the most essential weak points for the service life of the piston ring, in particular the compression piston ring.
Providing piston rings with hard coatings is generally known. However, in general these cannot prevent the partial phenomenon in the area of the ring joint ends. The radial pressure distribution can be optimized so that the joint pressure is reduced to relieve the joint areas. The introduction of radial cross-sectional weakened areas, preferably in the first and fourth quadrants, can cause a specific pressure relief. However, all measures together have not entirely remedied the phenomenon of joint overload, in particular in the case of piston rings constructed having an axially low height.
U.S. Pat. No. 1,278,015 discloses a piston ring, which is implemented as thinner in the joint area. The running surface of the piston ring is coated using tin, this tin layer being able to be implemented as thinner at the joint than in the remaining peripheral area.
A piston ring is known from JP 00120866 A, which includes a running surface, upper and lower flank areas, and an inner peripheral surface. The area of the inner peripheral surface is provided in the area of the joint ends with a cross-sectional weakened area.